Christie CP2220 image dropped out five times in a few minutes

[Guy Burns]

This problem relates to my AV being shown at the local cinema last Sunday. The signal went in from my Oppo Blu-ray player via a HDMI cable. I thought I had sorted out all the problems beforehand (see http://www.film-tech.com/vbb/forum/m...g-at-level-248), but a new one cropped up during the show. Five times during a 2-3 minute segment, the screen went black for maybe a second or two. I'd like suggestions as to why that might have occurred. I will be running this by the tech in a few days time, but I would like some suggestions before I do that.

The control room has four identical projectors in a large room (6 x 30m?), two on each side.


Where the problem DOES NOT lie
I can't be 100% sure, but I don't see the problem being with the following, for the reasons given.

1. Not the Oppo player. We've used the Oppo player at home for about 100 hours a year for the last 10 years and have never seen the image intermittently drop out. In fact, I don't think that would be possible, because if the video connection was lost, the projector and player would have to resync, and with my setup that takes about 20 seconds while re-sync messages appear on the screen. So any loss of image because of the player or HDMI cable would have been very obvious.

2. Not in the video itself. During production, testing, and previous showings over several years, I have watched this segment about 50 times. There are no short-term black dropouts. I've just watched it again and the segment is pure.

3. Not a power failure. One woman asked me after the show: "Did you have a power failure? I know what that looks like because it has happened at home – the Oppo will take about 30-40 seconds to reboot and sync.

4. Not a continuity failure. Other than the 1-second flashes to black, the AV didn't lose a beat. The video and audio were sharply lost, and sharply returned in sync, the video staying black for a second.

5. Not five 1-second lamp failures (as in faulty connection). If the lamp or its connections were somehow faulty, I wouldn't expect a sharp transition to black. I would expect a exponential fade to black over 1-2 seconds, like when you turn a slide projector off. Meaning that a 1-second light off, followed by a light on, would appear as a slight diminution, not complete blackness.


Two possible mechanisms
I can think of two mechanisms that could have caused the loss of light:

1. A mechanical barrier blocking the light, similar to what I can invoke in my BenQ PU9730. I can call up a Blank function which physically blocks the projector light with a metal disk.

2. The DLP chip has an intermittent fault.


Where the problem may lie
There must be some problem with the video signal after it gets inside the Christie CP2220 or the associated Doremi unit (I don't know what a Doremi is; it's what the tech told me some time back).

Now here's the thing: it was a 150 minute show. These blips occurred at around 115-120 minutes, at approximately the same time as I felt cool air on my back. I was in the back row and the air-conditioning had just kicked in.


Two Questions
Is it possible that an air-conditioner could cause transients that would interfere with the projector's light?

Any suggestions as to what might have caused the video blips?

[Randy Stankey]

Do you split the HDMI signal before it gets to the projector?

For instance, do you split the line so you can send it to a booth monitor or secondary screen?

I have had the screen intermittently blank out in the theater while the sound keeps going normally. The problem was caused by an HDMI splitter. For some reason, the splitter interferes with the encryption in the HDMI chain.

I don’t remember all the details because it happened a few years ago and I don’t work at that theater anymore.

Anyhow, the problem was solved by taking the splitter out of the chain.

[Marcel Birgelen]

This problem relates to my AV being shown at the local cinema last Sunday. The signal went in from my Oppo Blu-ray player via a HDMI cable. I thought I had sorted out all the problems beforehand (see http://www.film-tech.com/vbb/forum/m...g-at-level-248), but a new one cropped up during the show. Five times during a 2-3 minute segment, the screen went black for maybe a second or two. I'd like suggestions as to why that might have occurred. I will be running this by the tech in a few days time, but I would like some suggestions before I do that.

The control room has four identical projectors in a large room (6 x 30m?), two on each side.


Two possible mechanisms
I can think of two mechanisms that could have caused the loss of light:

1. A mechanical barrier blocking the light, similar to what I can invoke in my BenQ PU9730. I can call up a Blank function which physically blocks the projector light with a metal disk.

2. The DLP chip has an intermittent fault.


Where the problem may lie
There must be some problem with the video signal after it gets inside the Christie CP2220 or the associated Doremi unit (I don't know what a Doremi is; it's what the tech told me some time back).

Now here's the thing: it was a 150 minute show. These blips occurred at around 115-120 minutes, at approximately the same time as I felt cool air on my back. I was in the back row and the air-conditioning had just kicked in.


Two Questions
Is it possible that an air-conditioner could cause transients that would interfere with the projector's light?

Any suggestions as to what might have caused the video blips?

Without the possibility to reproduce the problem, it's a lot of guesswork what caused this particular problem.

It could very well be the starting HVAC equipment, depending on how much of a dip this caused on the local power grid and whether or not your player was connected to a UPS and how well your player is able to handle voltage drops. Many power companies have deployed capacitors into their distribution networks to combat the problems resulting from heavy equipment starting up causing significant voltage drops, but it can still cause a drop locally. The way equipment handles this, greatly differs between the type of equipment, although most modern equipment comes with buffered power supplies that will usually bridge a few seconds. Still, we used to have a HVAC unit at the office, that would produce a sufficiently great voltage drop to sometimes take the clock of the microwave in the kitchenette over the edge, which caused it to reset to 0:00...

Many critical cinema equipment like servers and the non-lamp-part of the projector are often put on a UPS, so it won't be directly impacted by such voltage drops. Stuff like xenon lamp houses and amplifiers usually have quite a buffer and aren't as affected by short voltage drops like many modern equipment.

Still, all of this remains a best guess.

PS: This projector doesn't have one DLP chip, it has three of them. The screen going blank without any artifacts on screen hints towards a total signal loss. Since there is barely any error-correction on the image part of HDMI, any interference will become apparent as garbage on screen.

[Guy Burns]

Splitter?
That's something I'll ask the tech. When I set up the Oppo, he handed me a HDMI cable. I doubt it went through a splitter, but it could have. So thanks. I'll definitely ask about splitters.

Artifacts?
No artifacts when the dropout occurred. Didn't think of looking for them at the time, but I do remember the dropouts as being very clean, and that the projector/player didn't have to handshake afterwards. Just went straight on playing.

There are a few other minor problems in this theatre (#4)…

• a very slight 50Hz hum;
• during solo piano sequences, the speakers had a slight buzz/rattle;
• and 6 inches or thereabouts of the top left part of the image was off screen (a 12-15m wide screen).

…so I may ask to be shifted to theatre #3. However, I was told that doing so was not desirable:

We do not recommend using cinema 3 as the projector is on a slight angle so the ratio would not be to your liking.

I originally went with #4 without thinking too much about the meaning of that statement. Reading it now, I'm thinking that it doesn't really make sense, and that I should ask to test theatre #3 to see what happens in there.


A Learning Experience
I'm learning something here. I assumed that cinemas everywhere would be presenting images and sound at the finest quality. I really did. I assumed I could just hire a theatre, walk in with my AV, and everything would look and sound better than in my home theatre. At this particular cinema, that's not the case. The quality obviously passes muster with the audience, so management are not overly concerned about small imperfections. I doubt anyone else heard the 50Hz hum, the piano buzz from the speakers, or saw the image extending beyond the screen at top left. And they certainly wouldn't be aware of colour errors in the projection system (there weren't any, in this case). Gone are the days of a Technicolor specialist on set, controlling the lighting (or whatever they did). These days how can you tell if that green skin under fluoro lights is through design, a bad scan, or because the projector is out of calibration? I have to be a bit picky, because most of my images are of wilderness areas and hikers, or indoor portraits taken with flash. I can't get away with strange colours like movies can.

Anyway, keep the feedback coming. I want to be able to present a few possibilities to the tech when I phone him in a few days about the dropout problem.

[Carsten Kurz]

As I said in the other thread - HDMI/consumer AV gear is the stepchild in digital cinema. An HDMI splitter/buffer may improve or worsen the situation. There is a good deal of voodoo with HDMI in professional installations.

Cinemas do not use these devices and connections in their daily business. The DCP playback mechanism is much more stable.

- Carsten

[Frank Cox]

I assumed that cinemas everywhere would be presenting images and sound at the finest quality. I really did.

As with anything else, there will be good ones and *cough* less good ones.

Some theatres are run by people who care about what everything looks and sounds like, and those people take steps to insure that the presentation is as good as it can be. Others are minimum-wage grab-as-much-as-you-can-as-fast-as-you-can operations, and I wouldn't expect great results there.

Some of the less well maintained theatres might disappear within the next while, as the zombie apocalypse has caused a shake-up in the industry.

[Dave Macaulay]

Where did that HDMI cable to connect to?
Older "Doremi" units (this is the data store and video/audio server for the regular movies) don't have an HDMI input so it would have to go to a scaler/switcher probably in the projector pedestal, maybe in the sound rack. Video to the projector is then via DVI, audio goes to the sound system from the scaler separately.
Newer ones do have HDMI inputs and pass the audio to the sound system. The HDMI cable would go directly to an HDMI connector on the side of the projector.
A xenon lamp going off for a second would be visible as instant black. There's some glow in the electrodes but they are not in focus at the light processor - and I can't see any fade-out on screen. But in a Christie CP2220 it doesn't restart in a second, and if it does... it damages the lamp.

The dropout happening with AC start says there's probably a short line voltage drop that messes up something in the signal path. Projector electronics can be on a UPS but rarely are. The Oppo without a UPS might hiccup on a voltage drop, a scaler or a server with HDMI might as well. If you do this again, get a UPS and have your Oppo and any scaler used powered from it.

[John Thomas]

You mentioned in point number 4 of your original post that you lost both audio and video together. So I would not consider any possibility of it being a DLP or light path issue.

As mentioned earlier, the likely culprit was the A/C. Lots of credit to you for making that connection -- most people don't notice that kind of thing.

Either the voltage drop from the A/C, or EM interference from the A/C's compressor would be the most likely culprits to me. More likely the voltage drop though, which could have affected anything from the bluray player itself to any scaler or splitter on that circuit. As stated before, a UPS (of decent quality) would clear that right up. Issues with EM interference could be mitigated by using a higher quality HDMI cable, or a fiber transmitter/receiver pair.

[Paul H. Rayton]

So, I'm assuming you are using this cinema space for your program on a rental basis, correct? As has been recommended a few times in the past to others, if you can't readily track down the problem you're experiencing, and it continues to happen, you could create a completely different route of signal delivery by converting your presentation(s) to DCP. The program "DCP-O-Matic" is frequently discussed in this forum, and has all the capabilities you'd need to create the DCP. Then, you'd hand over your DCP to the cinema a day or two before your show, have them ingest it and preferably do a screen check of it with you present, and then it's ready to play at the scheduled time. As Carsten mentioned above, the DCP playback chain is much more stable than using mysteriously-wired consumer equipment.

One caveat -- be sure to test your DCP, or at least a portion of it, well in advance, to make sure the DCP you are making is fully compatible with their installed cinema projection equipment. The process should be very straightforward, but ... one of the gremlins that we in the operations end of things have frequently faced recently are DCPs that are made by non-professionals, and occasionally things are not always "just so" and require revising. You don't want to discover that 30 min. before your scheduled event!

[Leo Enticknap]

As Paul knows (because he was my boss there!), I was a big advocate of DCP-izing alternative content in my days at the Egyptian. If we're talking about one or two shows a week, and you can leave the computer in the booth rendering overnight, I would do that every time. But if the volume of stuff is such that this isn't feasible, or you can't get your hands on the source material in time to do it, you've got to try to make playback thru HDMI work.

As I said in the other thread - HDMI/consumer AV gear is the stepchild in digital cinema.

I would characterize it more as the result of incest between professional cinema and consumer media (as in, this charming movie!).

Cinemas do not use these devices and connections in their daily business.

Actually they do; here, at any rate. The Screenvision streaming advert players send video into the media block or input board via DVI/HDMI, for example. But there is no HDCP with it, so 99.9% of the problems are never there to start with.

Where HDMI is unavoidable, I like the HD Fury device for ironing out gremlins. It's a bit pricey, but I have never once deployed one and failed to have it solve a compatibility problem. Its USB interface enables one to hook it to the remote access PC, for remote troubleshooting of color space and other issues, too, if a theater decides to hook a new HDMI device to it and has pix and/or audio problems.

[Guy Burns]

Thanks for the feedback and suggestions, all to no avail unfortunately. They didn't take kindly to my wanting to find out where the problem lies:

I can assure you it is not our equipment… It was your choice to use your equipment above ours. We have never had any "dropouts" and the air conditioning runs in there everyday. We are not at liberty to disclose any details of our equipment for security purposes. We will not risk screening any further of your productions as they are obviously not compatible with our equipment.

Oh well, I tried. At least I had one viewing of my AVs on the big silver screen. Actually, it doesn't bother me too much. On the drive back from the cinema last Sunday I was thinking: "I can't handle those dropouts. I'll have to cancel future plans." Now they've made the decision for me. So it's back to the good ole PU9730 at the local civic centre…

Leven Theatre.jpg

And there's nothing wrong with the local: for less than $200 (and that's Australian dollars), I get 250 tiered cinema-style seats, a superb sound system, access on Friday and Saturday nights, and no rushing around – it's mine from midday till midnight. Why did I ever bother with the cinema!

Thanks again.

[Marcel Birgelen]

I guess your experience depends on your cinema too. Many smaller theaters I know, are quite willing and patient to stage alternative viewings via alternative means. You can't expect them to mess around with their equipment beyond a certain level though, as this stuff costs a lot of money and it's their livelyhood.


Like indicated before: The safest way of getting your content into the cinema and on-screen the way it should be, usually is via a DCP. That's what cinemas normally play and as long as yours conforms to the standard and the cinema did their homework, stuff should normally just work out fine.

I guess there are still some learning curves, like how to correctly frame content used in cinemas, as you can't expect your image to be integrally projected corner to corner on each and every setup out there.

No matter where you go, once you start plugging in your home AV equipment into the existing equipment, you can expect some troubles. Although the professional A/V industry and home A/V technology are increasingly coming together, there still is a distinctive gap between both of them that you need to negotiate when bringing them together.

[Jim Cassedy]

I work in several private rental screening rooms, & theaters and also am also a contractor with the Union that does AV work at many of the large conventions & hotels here in SF. Being a veteran of many film festivals and 'film-maker' screenings, we ALWAYS try dissuade people from bringing in their own equipment. Even at some of the big trade shows, we even strongly discourage people from bringing in their own computers when doing Power-Point presentations. (We actually keep a stash of fairly recent model computers, mostly MACs & PC's just for client presentations. They are wiped clean after every show.) There are just TOO MANY variables with customer equipment that can muck things up, and tie up several members of the tech staff twiddling around trying to get a client's equipment to interface seamlessly with the professional systems. (and, broadly speaking, minimum wage for someone performing this work is $37.50/hr, with most of us getting paid quite a bit more. So "dead time" adds up quick when you've got a crew dicking around to fix a problem that wouldn't have happened if the client took our advice.) Sometimes there are minor differences in video & audio output cards & drivers - - even between two computers of exactly the same make & model and running the same OS, but which were manufactured several several weeks apart.

And, interfacing "home" grade or even hi-end Blu-Ray decks & computers to DCP compliant equipment opens another whole technical "can of worms" that sometimes must be dealt with. As others have mentioned, HDCP can be a big headache. Most of us who do this often usually know some 'tricks' that can get things working. But sometimes what works with one deck & ICP won't work on another. One way around this, as others have mentioned, is to directly use the DVI inputs on the projector. But depending on the theater and the competency of their staff, they may not know they HAVE DVI inputs in their system, and if they do, there's a good chance it hasn't been set up properly. (If at all) It also requires you've got the necessary HDMI to DVI adapter cables available, and then you're also going to have to handle the audio separately. (and good luck with that at many theaters whose staff actually knows little to nothing of how things work beyond the popcorn machine)

- - and I can't count the times I've almost thrown my optic muscles out of wack trying to fight the invertible reflexive eye rolling that occurs after every time I've heard the phrase: "but it worked (or looked, or sounded) just fine when I played it at home".

The "almost" bullet-proof" solution is to show up with a DCP. Either commercially made, or rendered yourself using one of the readily available programs, such as "DCP-o-Maitc" mentioned here. While, as they say in North Korea: "It's not rocket science", the process isn't really 100% intuitive and so it helps to render a short 'practice' DCP or two before your big event. I, and others here, can also relate horror stories of self-produced DCP's brought in to a film festival or for a screening that were rendered completely out-of-spec, or were given to us on incorrectly formatted thumb drives that also contained a lot of other garbage and unnecessary files which caused the DCP servers to gag on ingestion, or not even recognize the drive.

At one event venue, we'd still prefer that people brought in their stuff on 35mm film, but we also realize that's not an option for many. (but I'm sure God has a special place in heaven for those who do)

[Marcel Birgelen]

God also has a special place somewhere for people that ruin precious 35mm stock with garbage.